A variety of devices and systems have been designed for use in injecting fluids and other dry soluble products into fluid streams. Such devices/systems include, for example, metering pumps, water powered pumps, siphon devices, flow through devices, gravity feed drainage equipment, etc. However, various problems are encountered with each type of device/system currently available in delivering an accurately proportioned injection amount, whether the injected product is a fluid or solid.
Metering pumps can either be set to inject a predetermined amount of product into a fluid stream without any means of adjusting to changes in flow volume in the fluid stream, or they can be set for electronic control by flow sensors located in the fluid stream. A disadvantage with metering pumps is that the components of this type of system are mechanical and electronic, so they are subject to wear and mechanical failure
Water powered pumps adjust automatically to changes in flow in the fluid stream, but have the disadvantage that they are a mechanical device with a number of seal points. These seals require frequent maintenance for the unit to operate properly and not leak. Additionally, water powered pumps are generally limited in the amount of fluid flow they can operate with and, as the flow increases, the complexity and cost of the device will also generally increase.
Siphon devices generally rely on a high restriction in the fluid stream to create a venturi-type suction strong enough to pull the injection solution from the storage container into the fluid stream. However, siphon devices require high pressure to operate, and the high restriction in the fluid stream greatly reduces the fluid stream volume. A disadvantage is that fluctuations in pressure can cause the siphon device to not inject continuously, thus creating uneven distribution of the product into the fluid stream. Additionally, siphon devices are also unable to dependably inject solutions, such as water-soluble fertilizers, without plugging.
Venturi-type systems generally have relatively small flow orifices and, thus, the fertilizer solution has a tendency to settle. Such settling tends to create sedimentation that plugs the orifices causing system failure.
Flow through devices typically channel, or direct, the flow of the fluid stream through a container that holds a soluble product that slowly breaks down, releasing the product into the stream. However, flow through devices generally do not control the amount being distributed and can provide unreliable distribution into the fluid stream. It is also common for the soluble products to melt as they sit in the water in the tank while the system is not operating, resulting in a large amount of the soluble product being released when the system is restarted.
Several types of fluid injectors have been developed to proportion liquid or soluble fertilizers or chemicals into fluid piping systems. For example, U.S. Pat. No. 5,484,106 (the “'106 patent”) accomplishes such a proportioned injection, but relies on a check valve to prevent the backflow of contaminants into the fluid stream. With this design, the outlet flow port connection needs to extend to the bottom of the storage tank to establish a consistent injection rate of fertilizers, which tend to have a higher specific gravity than the incoming water. When the outlet port connection is extended to the bottom of the storage tank, the system may develop an air pocket in the top of the storage tank that can only be eliminated by manually filling the tank with fluid, or by some other means of manually venting the system. If the air is not removed from the system, a potentially hazardous condition exists. Since air compresses under pressure, this creates a higher stress on the storage tank than fluids under pressure, and can cause the storage tank to rupture at much lower operating pressures. The presence of air also reduces the amount of fluid in the storage tank. This, in turn, limits the fluid available to mix with soluble products to turn them into an injectable solution, causing the system to not inject accurately or, possibly, to not inject at all due to plugged flow ports. Since there is no way for air to escape the storage tank, soluble products must be premixed and the tank filled with water before using the system. Many soluble products begin settling to the bottom of the tank immediately after being mixed, and continuous agitation is required to keep them in an injectable state. This requires extending the inlet port to near the bottom of the storage tank to direct flow through the soluble product and keep the product mixed. Also, the '106 patent design does not provide a means of injecting more than one solution from the same tank at independent ratios.
U.S. Pat. No. 4,846,214 (the “'214 patent”) has an automatic mechanical air relief valve that vents air from the storage tank to the atmosphere. While it does evacuate the air from the tank automatically, the device is mechanical in nature so it is subject to wear and eventual failure. Additionally, it does not provide backflow protection, establish proportioning rates, or allow air to be vented through the piping system. Further, it also does not provide a means of injecting more than one solution from the storage tank at independent ratios.
U.S. Pat. No. 3,809,291 (the “'291 patent”) discloses a gravity feed system that uses an internal mixing chamber to combine two liquids to be dispensed into a fluid stream. It requires an electrical controller, a pressure switch, and a float valve to control fluid flow into the tank.
U.S. Pat. No. 5,544,810 (the “'810 patent”) utilizes a high pressure flow line to create a venturi-effect to draw multiple fluids from multiple unpressurized containers and accurately mix them into one solution. The system has an air vent to the atmosphere to prevent siphoning of fluid from the storage containers when the system is not operating. However, this design requires a high-pressure flow line to create enough vacuum to draw the mixed fluids from the containers. This creates a high restriction in the flow line, significantly reducing flow volume and pressure. It also requires multiple containers to store the various solutions, which requires piping connections between all of the containers used. Additionally, the '810 patent design cannot operate at low pressures or automatically mix dry products and keep them as an injectable solution.
U.S. Pat. No. 6,039,065 (the “'065 patent”) discloses a mixing valve that combines liquids at controllable proportions. However, it does not provide for the injection of liquids into a flow line; only the mixing of incoming flows.
The above described patents are only exemplary of some of the devices currently known, and are not meant to provide an exhaustive list.
None of the current solutions accurately measure the injection rate of an aspiration type of injector. This is due to the continuous dilution of the mix in the tank, and/or not being able to measure the water flowing into the storage tank. The current solutions also cannot inject a small, continuous amount of a product into high flow rate. For such applications, pulse injectors are typically used. However, pulse injectors inject a small pulse of product every so often, which is less desirable than a continuous injection stream. Further, the current solutions cannot be interchangeably used effectively with both liquid and dry products.
The present disclosure is directed toward overcoming one or more of the above-identified problems.